On Fri, Nov 20, 2015 at 5:12 PM, Rahkonen Jukka (MML) < [email protected]> wrote:
> I tried again with the brand new Geoserver 2.8.1. GetCoverage for the > whole mosaic (4 images, 12000 x 12000 pixels each) was now successful. The > 1.6 GB output GeoTIFF is good. Memory consumption during the process with > 32-bit jre and default java settings was no more than 360 MB. It took 1 > minute and 40 seconds to get the image with curl. So far I was happy. > > > > But there is something odd in how the service behaves. It took whole 15 > minutes to serve the coverage with the very first time I made the > GetCoverage reques but after that it was quite fast and I thought that > everything is OK. But then I tested what happens if I send two 1.6 GB > GetCoverages from two distinct curls. After 70 minutes I made a conclusion > that even the process was still alive it was for sure all too slow for > being useful and I killed curls. Unfortunately even after killing the curl > jobs the java.exe that runs Geoserver continued to use 20% of CPU and burn > my hard disk. That stopped finally perhaps after 10 minutes. > Yep, this is happening because we cannot stream the tiff out directly, we have to write it on disk first and return it later. And the HTTP protocol is setup in such a way that one can notice the client is no more there only by writing bytes out to it, so killing the client request does exactly nothing unfortunately, GeoServer keeps on processing until the tiff is fully written, and then discovers the client is not there anymore when trying to write out the first byte to the response socket. If you have a 32bit JRE it might be that you don't have enough memory allocated to the java runtime, which will make the two requests compete for the entries in the tile cache, one stealing cached tiles from the other, hampering progress.... the only thing I can recommend if this is the case, is to give GeoServer more heap. It would be interested to simulate this load and see if we can do anything to improve things on lower heap systems... but, gut feeling, it may require a few days of work > > > It seems to be very unsafe to publish even a pretty small image mosaic > like my four-image test mosaic as WCS without setting Resource Consumption > Limits. Perhaps Geoserver should set some rather small default values for > the limits instead of setting no limits like it does now. And if it is > really so easy to make WCS to jam by sending many concurrent requests it > might be good to mention the Control flow module > http://docs.geoserver.org/stable/en/user/extensions/controlflow/index.html > in http://docs.geoserver.org/stable/en/user/webadmin/services/WCS.html. > Yes, agreed, both good ideas. You might want to open a ticket for the first one at least. On, on the master series we have a coupe extra improvements that you might want to check out using a nightly build: http://ares.boundlessgeo.com/geoserver/master/ For large extractions WCS is not a suitable protocol anyways, as it does not have a asynchronous mode, you might want to have a look at the WPS download module instead, it's a community module that we created with the sole purpose of replacing WFS/WCS for large extractions where the asynch call support is a must. Cheers Andrea -- == GeoServer Professional Services from the experts! Visit http://goo.gl/it488V for more information. == Ing. Andrea Aime @geowolf Technical Lead GeoSolutions S.A.S. Via Poggio alle Viti 1187 55054 Massarosa (LU) Italy phone: +39 0584 962313 fax: +39 0584 1660272 mob: +39 339 8844549 http://www.geo-solutions.it http://twitter.com/geosolutions_it *AVVERTENZE AI SENSI DEL D.Lgs. 196/2003* Le informazioni contenute in questo messaggio di posta elettronica e/o nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il loro utilizzo è consentito esclusivamente al destinatario del messaggio, per le finalità indicate nel messaggio stesso. Qualora riceviate questo messaggio senza esserne il destinatario, Vi preghiamo cortesemente di darcene notizia via e-mail e di procedere alla distruzione del messaggio stesso, cancellandolo dal Vostro sistema. Conservare il messaggio stesso, divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo, od utilizzarlo per finalità diverse, costituisce comportamento contrario ai principi dettati dal D.Lgs. 196/2003. 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